The present invention relates to cleaning boiler tubes and particularly to a rotary scrubber for cleaning tubes.
Commercial tube cleaning equipment ordinarily uses a rotary brush for cleaning the inner surface of tubes and pipes of power plant equipment and machines such as boilers, chillers, condensers, heat exchangers, absorption machines and so forth. These brushes have a twisted steel wire spine securing bristles as illustrated in U.S. Pat. No 5,235,718.
In operation, conventional tube cleaning equipment passes the rotary brush through each tube to scrub soot and dirt from the tube surface. The rotary brush is accompanied by a stream of water to flush scrubbed soot and dirt from the tube.
Standard brushes are sized specifically to tube size so that for tubes of different diameters, separate sized brushes must be used for efficient tube cleaning. In addition, brushes wear down and must be replaced from time to time.
The twisted steel spine of the rotary brush can mar delicate tube walls.
The stream of flushing water injected into a tube backs up behind the rotary brush and there is a back flow of flushing water when the rotary brush is retracted from the tube after a cleaning pass.
The present invention is directed to a new and useful scrubber that surpasses the limitations inherent in use of standard bristle brushes for tube scrubbing operations.
A tube scrubber according to the invention comprises a one piece elongate body symmetrical about its longitudinal axis, having a central core with threaded stem for connection to a rotary driving device, and a plurality (preferably three) of flexible wing-like arms or webs extending outward from the central core and terminating in longitudinally extending cutting edges which scrub dirt or soot from the inner surface of a boiler tube and the like.
The central core is essentially a round shaft with imaginary parallel longitudinal surface lines (preferably three) spaced 120xc2x0 circumferentially about the shaft such that the imaginary lines define places of attachment of the flexible arms to the core.
Each flexible arm is a web-like curved plane preferably approximating the shape of one-fourth of a cylinder wall defined by parallel inner and outer edges. The inner edge of each flexible arm is integral with the core along one of the imaginary lines with the arm projecting outwardly from the core curving approximately 90xc2x0 from the line of attachment and terminating at the outer edge. The outer edge includes an integral cutting edge for engaging and scrubbing tube walls.
The flexible arm construction allows the scrubber to compensate for wear in that the arms flex outwardly to maintain engagement with tube surface as the arm cutting edges wear in use.
So, the scrubber preferably includes three longitudinally extending cutting edges, with the edges being spaced approximately 120xc2x0 apart for scrubbing engagement with the cylindrical inner surface of a boiler tube, for example. The flexible arm design enables use of the scrubber in a one-eight inch range of tube diameter sizes in contrast to conventional brushes which are limited to use in a single tube size. The cutting edge configuration results in self sharpening of the scrubber edges as they engage and scrub tube walls.
The spaces between adjacent flexible scrubber arms define longitudinal passages through the scrubber for free flow of flushing water in a tube particularly as the scrubber is retracted from the tube after each cleaning pass.
The length of each flexible arm and its cutting edge is approximately the same as the length of the elongate core body of the scrubber.
The scrubber is preferably fabricated of a durable plastic such as nylon.
By way of comparison to a conventional bristle brush, the present invention provides a tube scrubber that cleans a tube twice as fast for the same feed rate of the scrubber through a tube, provides a single size scrubber for a range of tube diameter sizes, does not mar delicate tube surfaces, self-compensates for wear, self-sharpens its cutting edges, and allows faster flow of flushing water when retracting the scrubber from a tube.
An object of the invention is to provide a tube scrubber that surpasses limitations inhering in use of conventional bristle brushes.
Another object of the invention is to provide a one-piece tube scrubber with flexible scrubbing arms wherein a scrubber of one size is useful in a range of tube sizes and wherein the flexible arms self-compensate for wear.
Another object of the invention is to provide a one-piece tube scrubber with flexible scrubbing arms having longitudinal passages between adjacent arms to accommodate free flow of tube flushing water past the scrubber in the course of tube scrubbing.
Another object of the invention is to provide a one-piece tube scrubber with flexible scrubbing arms with self-sharpening cutting edges.
Other and further objects of the invention will become apparent with an understanding of the following detailed description of the invention or upon employment of the invention in practice.